Methods of making transgenic animals producing oligosaccharides and glycoproteins

A method for producing a non-human transgenic mammal whose somatic and germ cells contain a transgene, wherein expression of the transgene results in the production of oligosaccharides or glycoproteins in the milk of said mammal, the method comprising the steps of:

• (a) preparing a transgene which encodes a heterologous glycosyltransferase;
• (b) methylating said transgene;
• (c) introducing the transgene of step (b) into fertilized eggs of a non-human mammal such that the transgene is integrated into the genome of the fertilized eggs;
• (d) culturing the eggs which result from step (c) to pre-implantation embryos;
• (e) removing at least one cell from each of said pre-implantation embryos, and lysing at least one cell;
• (f) incubating DNA molecules released in step (e) with a restriction endonuclease which cleaves said methylated transgene but does not cleave an unmethylated form of the transgene;
• (g) identifying those embryos of step (e) which contain the methylated transgene integrated into their genome;
• (h) implanting at least one of the embryos identified in step (g) into a recipient female;
• and
• (i) developing to term said non-human transgenic mammal, where the expression of said transgene results in the production of oligosaccharides or glycoproteins in its milk.